SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '874d973ee76bf893c24cef7b79adea7a665d760b7fe925f9cfcd25e870578fbe' 
  AND token = 'gQZnRNT78ydLB+uwprxpHbVIfQMVxB/CKHeLNFqbIKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}